The Solar System and Earth's Atmosphere

Asteroid

bodies of rock and ice in space

Atmosphere

layer of gas around the planet

Comet

a body of ice, dust, and bits of rock that passes through space

leaving a tail of ice and dust behind it.

Day

The length of time it takes the Earth to spin all the way around so that you get a

night and a day

Galaxy

A large group of stars, all orbiting a central point.

Gravity

The force that attracts a moon to a planet, or a planet to a star.

Light Year

The distance that light travels in one year: 5.9 trillion miles

Meteor

small piece of debris in space, up to the size of a boulder

Milkyway

The galaxy that we live in

Moon

a smaller object orbiting a planet.

Orbit

The path that a planet takes around the Sun, or that a moon takes around a

planet.

Planet

large body of either rock or gas that follows a consistent orbit around a star

Planetesimals

Objects, from tens to hundreds of kilometers in diameter, that formed

in the solar nebula as an intermediate step between tiny grains and the larger planetary

objects we see today

Shooting star

a meteor that is passing through

the Earth's atmosphere and has gotten so hot that it glows in the night sky.

Solar System

The Sun and the collection of stars

Solar nebula

The cloud of gas and dust from which the solar system formed

Star

a huge ball of very hot gases held together by gravity and that gives off

lots of light and heat.

Sun

The star in our solar system. The center of our solar system

Universe

everything that exists

Year

The length of time it takes the Earth to travel around the Sun, 365 days.

Mercury

Planet closest to the Sun a rocky planet with 88-day orbit; no atmosphere.

Venus

Similar in size to Earth; thick toxic atmosphere; hottest planet (460°C);

Earth

Only known planet with liquid water and life

Mars

It is red due to iron oxide and has thin atmosphere

Jupiter

The largest planet also known as a gas giant with over 60 moons and massive storms.

Saturn

Gas giant known for its ice/dust rings; second largest planet

Uranus

tilted axis causes extreme seasons; 84-year orbit; coldest planet.

Neptune

The planet farthest from the Sun

Pluto

A dwarf planet that didn't clear its orbit

Observation

Using senses to gather information (e.g., sight, sound).

Hypothesis

Testable prediction (educated guess) about cause and effect.

Inference

Logical interpretation based on observations or evidence.

Theory

A well-supported explanation for a wide range of observations.

Independent Variable

A variable that the scientist can change.

Dependent Variable

The variable that is measured (the effect).

Controlled variable

Kept the same to ensure a fair test.

bar graph

Compares quantities or categories over time.

line graph

Shows trends or changes across time periods.

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Pie chart

Shows parts of a whole as percentages or proportions.

Data/Dataset

The information or sets of information gathered during an experiment or survey.

Base Units

Standard units for base quantities

Derived Units

Calculated from algebraic combinations of base units.

Replication

a good scientific research must be able to be repeated by other researchers and get the same results.

Falsifiable

good theory or hypothesis must be possible to be rejected, otherwise the research will present confirmation bias.

Troposphere

Closest to Earth where weather occurs; most dense.

Stratosphere

Contains ozone layer; temperature rises with altitude.

Mesosphere

Meteors burn here and is very cold.

Thermosphere

Satellites orbit here; contains auroras and ionosphere.

Exosphere

Outermost layer and merges into space.

Hydrosphere

Water in all forms—liquid, ice, vapor.

Geosphere

Solid Earth—rocks, land, soil

Biosphere

All living organisms.

Cryosphere (sub-sphere)

Frozen water—glaciers, ice caps.

Minerals

Natural, inorganic solids with a definite chemical structure.

The three rock types

Igneous

Sedimentary

Metamorphic

igneous rock

Cooled magma/lava.

Sedimentary

Compacted sediments.

Metamorphic

Changed by heat/pressure.

Rock cycle

Continuous transformation among the three types of rock

Weather

Daily conditions

Climate

Long-term weather trends in a region.

Weather Elements

Temp, humidity, wind, clouds, precipitation, pressure.

Tropical

Hot and humid (rainforest, savanna)

Dry Climate

Arid and semi-arid (deserts, grasslands).

Mild Climate

Moderate temperatures (Mediterranean, humid subtropical).

Continental

Seasonal extremes (hot summers, cold winters).

Polar Climate

Tundra and ice cap—cold year-round

Water vapor

Varies with altitude; essential for weather.

Aerosols

Tiny particles from natural & human sources; affect clouds and climate

Greenhouse gases

Trapped heat usually made up of CO₂ and CH₄

Pollutants

harmful to health and ozone.

The seven physical properties of

Color

Streak

Luster

Cleavage

Color

The hue of the mineral

Streak

Color of mineral's powdered form

Luster

The way light reflects off the surface of the mineral

Cleavage

tendency of a mineral to break along specific planes.

Fracture

The way a mineral breaks when it does not cleave, resulting in irregular surfaces.

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Crystal form

The geometric shape in which a mineral naturally occurs if allowed to grow without

interference.

Hardness

The resistance of a mineral to being scratched, measured on the Mohs scale.

Cloud Cover

Indicates the amount and types of clouds present in the sky, influencing temperature

and precipitation.